Turbine apparatus



Nov. 7, 1961 T. J. RAHAIM ETAL TURBINE APPARATUS Filed Aug. 31, 1959 STATION-A STATION-B INVENTORS THOMAS J. RAHAIM KENNETH L.R|EKE BY I 7 United States Patent G Filed Aug. 31, 1959, Ser. No. 836,976 3 Claims. (Cl. 60-3932) This invention relates to turbine apparatus, and more particularly to improved means for supporting a com-buster of a" gas turbine or the like.

A conventional gas turbine COmbllStOT comprises a perforated, tubular basket providing a combustion chamber and a tubular shell which surrounds the basket in spaced and concentric relationship. Compressed air is usually introduced to the annular space between the basket and the shell adjacent the upstream end of the combustor. Some of this compressed air cools the outer surface of the basket as it flows downstream; and the rest of the air flows through the basket perforations into the combustion chamber to" support combustion and/or cool the inner wall surface.

Hot spots and thermally stressed areas in the basket can be caused by one part of the basket being closer to the flame than other parts. It is desirable, therefore, for the basket to be held in concentric relationship to the flame in the ease of one flame, or in concentric relationship to 3111 annular array of flames where there are several of Hot spots are also attributable to the basket support members they resist the thermal expansion of the basket too forcibly. At least one previously proposed basket support is capable of yielding readily to the expanding basket but is ineffective for resisting axial forces on the basket and bracin it against rocking vibrational movements. Therefore, it is the concern of the present invention to provide a supporting arrangement which yields easily to thermal expansion of the basket all directions and braces the latter against vibrational movements as well as large axial forces. Principally, however, the invention is concerned with accomplishing the foregoing while retaining the basket in concentric relationship with the shell. By retaining this concentric relationship it is insured that the am ular air duct will be of uniform thickness and that the air flow through the air duct will be symmetrical, or balanced.

According to the present invention, the combustor basket is supported from the shell at axially spaced stations by improved supporting means. The latter includes, for at least one station, aplurality of strut members, each disposed tangentially relative the basket and in a plane normal to the basket axis. A plurality of braces, extending at an acute angle to the basket axis, supports the basket at another station. All of the strut members and braces are flexible and each connects the basket to the shell.

Preferably the strut members are equally spaced in an annular array; and the braces are alsoin an annular array, but extending in converging relation to one another and the basket axis.

With the arrangement of the present invention, axial forces are transmitted to the braces and the latter are defiectable laterally as the basket expands radially and fill-J cumferentially. The braces hold the basket against axial movement and permit the basket to undergo thermal. expansion in an direction relative the connection between the basket and the braces. Meanwhile, the strut members undergo deflection axially and radially as the basket expands.

The various objecm, features and advantages of the invention will become apparent from the following description and claims taken in connection with the accom- 3,007,308 Patented Nov. 7, 1961.

2 panying drawings, forming a part of this application, in which:

FIG. 1 is a view, partly in elevation and partly in section, of a combustor embodying the invention;

FIG. 2' is a sectional View taken along line Ill-II of FIG. 1 showing the c'ombustor support structure at one station on a basket section;

FIG. 3 is a View similar to FIG. 2 but taken along line III'HI of FIG; I to show the combusto-r support structure at another station on the same basket section; and

FIG. 4 is a perspective viewof a fragment of the combustor of FIG. 1 with portions of the shell broken away.

Referring to the drawing in detail, the invention is shown embodied in a combustor of the type used in industrial gas turbines; however, it is not so limited.

A combustion chamber 9 of the combustor is provided by an elongated tubular basket, made of metal and designoted as a Whole by the numeral 10; As shown, the basket comprises three, independently supported sections 12, 14 and 116 which are arranged serially and with their juxtaposed open ends telescopcd one within the next, respectively, in spaced, axiallyoverlapping relationship so that they are relatively movable in axial direction. The basket walls are of substantially circular cross section and provided with perforations I7.

Enclosing the basket 10, in spaced and concentric relationship with the walls thereof, is a tubular metal shell 18 of circular cross section. The shell 18 includes wall structure formed about an axis transverse tothe basket axis and defining a pair of large inlet openings 19 for admittingcompressed air to the upstream end portion of the shell.

The annular space between the shell 18 and the basket 10- provides an air duct 20 through which some of the compressed air flows downstream toward the turbine (not shown) and along the length of the combustor basket. Some of the air passes through the basket perforations 1'7 and enters the combustion chamber 9 where a portion thereof supports the combustion of injected fuel; and the rest of the air flows downstream with the products of combustion.

' In order to minimize the temperature gradient across the basket wall, and thusavoid high thermal stresses, the Wall of each basket section 12, 14 and 16 is made as thin as is permissible, taking into account the importance of the basket 10 retaining a circular cross section under operating conditions. It is equally important that the basket be free to expand axially, radially, and circumferentially, without being deformed due to resistance from a basket support member. Nonetheless the basket 10 must e r ed o that i l not de e t pp e ab y ue to vibration and/or axial forces. The latter is particularly important when the combustor has its: axis disposed vertically and the force of its weight is directed axially.

The basket sections 12/, 1-4. and 16, are each independent- 1y supported from the shell 18v at two stations A and B, which stations are spaced, axially apart an appreciable distance along the length of the basket section, At both A. and B stations there is an annular array of strut members 26 disposed in the air duct 20; preferably four members, as shown, but the invention is not so limited. The strut members 26 are spaced apart equally in a, plane normal to the basket axis and they are disposed substantially tangentially relative the basket 10.

Each strut member 26 is a slender, flexible part preferably made of steel, its outer end being rigidly secured to the shell 18 by suitable means. The inner end; of each strut member 26 is pivotally' secured to the basket 10 so that these parts are relatively movable about an axis that is generally parallel to the basket axis. Elongation of the strut members 26 due to thermal expansion causes the basket 10 to rotate a small amount relative its axis, but

the basket and shell 18 remain concentric. The ability of the basket and the shell 18 to remain in concentric relationship is important because it insures a symmetrical air flow through the air duct 20, as is well known in the art.

At each B station there is, in addition to the tangential strut members 26, an annular array of braces, or second strut members, 28.

It is preferred that the members 26 and 28 be of circular cross section, or that they each have a cross-sectional extent which is the same in directions which are transverse to its longitudinal extent and at right angles to each other.

The braces 28 extend at an acute angle to the basket axis in converging relation to one another and toward a common point along the basket axis. Just like the tangential strut members 26, each brace 28 is a slender and flexible part preferably made of steel, its outer end being rigidly anchored to the shell 18 by suitable means. Preferably there are as many braces 28 at station B as there are strut members 26; and the inner end of each brace is joined to the inner end of an associated strut member by means of a clevis-like pivotal connection 29 (see FIG. 4). In this regard, the inner end of each brace 28 serves as a pivot pin and is received in the connection 29 adjacent the end of its associated strut 26. The strut 26 is, in turn, pivotally connected to an ear or lug '32 of the basket 10, as by a pin or bolt.

In operation, each of the basket sections 12, 14 and 16 expands in an axial direction relative station B, which is more or less a base point subject to axial displacement only as a result of the braces 28 elongating due to thermal expansion. The juxtaposed ends of neighboring basket sections are in overlapping and radially spaced relationship, so that neighboring basket sections are free to move relative each other. As mentioned previously, thermal expansion of the tangential strut members 26 causes basket rotation relative its axis, but the basket and shell remain in concentric relationship. The circumferential expansion of the basket 10 produces a radial enlargement thereof which is only lightly resisted by the flexible parts 26 and 28. In other words, the strut members 26v and the braces 28 are easily deflected in a radial direction, because their circular cross section gives them the ability to flex laterally in several directions about their rigidly anchored outer ends. Though easily deflected laterally, it can be readily appreciated that the braces 28 are positioned in such a manner that they can forcibly resist even very large axial forces, such as those attributable to thrust forces of the gases and/or the weight of the basket when the combustor axis is arranged vertically.

As best seen in FIG. 1, the basket 10 spans large inlet openings 19 in the shell 18 which are disposed radially outwardly from overlapping end portions of neighboring basket sections. The present supporting arrangement is particularly well suited for this task, since the B stations of the neighboring sections 12 and 14 are then arranged adjacent each other, extending at least partly across the inlet openings 19. The overlapping ends of neighboring basket sections are thus supported in cantilever fashion from portions of the shell 18 substantially removed from the inlet openings 19.

An obvious modification of the present arrangement is to eliminate tangential strut members 26 at B stations for applications requiring a minimum amount of radial support at one end of a basket section. In this situation the braces 28 alone provide some support in the radial direction at station B.

From the foregoing it will be apparent that a supporting arrangement for a combustor basket has been provided which not only yields easily to the thermal expansion of the basket in all directions and provides a large measure of resistance against axial forces and vibrational movements, but also maintains the basket centrally of the shell during operation.

While the invention has been shown in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof.

What is claimed is:

1. A gas turbine combustor comprising a tubular basket having a perforated wall of circular cross section formed about an axis, a tubular shell of circular cross section radially spaced from said basket wall and concentrically arranged with respect thereto to provide an air duct therebetween, and improved means disposed in said air duct for supporting said basket from said shell at a plurality of Sta tions; said supporting means at one station including a plurality of flexible strut members each connected at its outer end to said shell and pivotally connected to said basket at its inner end, said strut members being arranged tangentially relative to said basket wall and disposed in a plane normal to said basket axis, said supporting means at said one station further including an annular array of braces each connected to said shell at its outer end, means providing a pivotal connection between the inner end of each brace and said basket adjacent the respective inner ends of said strut members, said braces extending at an acute angle to the basket axis in converging relationship with each other and said axis toward a common point on said axis.

2. A gas turbine combustor comprising a basket including at least two tubular sections each having a wall of circular cross section formed about a first axis, said basket sections being serially arranged with their juxtaposed ends axially overlapping and in radially spaced relationship, a tubular shell of circular cross section surrounding said basket in spaced and concentric relation thereto so as to define an annular space therebetween, said shell having wall structure formed about a second axis transverse to said first axis to provide an inlet thereto which overlies the overlapping ends of said basket sections, and improved means disposed in the annular space between said basket and said shell for independently supporting each of said basket sections from said shell at first and second stations spaced apart in the direction of said first axis, the respective second stations being disposed adjacent the overlapping ends of said baskets, said supporting means at each of said first and second stations including an annular array of strut members each connected at one end to said shell and pivotally connected at the other end to said basket, said strut members at each station being spaced apart in a plane normal to said basket axis and disposed substantially tangentially relative to said basket wall, said supporting means at each of said second stations including 7 an annular array of braces connected at one end to said shell, and means providing a pivotal connection for the other end of each brace at said basket adjacent the respective other ends of said strut members at said second station, said braces extending at an angle to the basket axis in converging relation to one another and said first axis.

3. A gas turbine combustor comprising a tubular basket having a wall of circular cross section formed about an axis, a shell surrounding said basket in spaced relationship so as to provide an annular space therebetween, and improved means for supporting said basket at a plurality of axially spaced stations within said shell and in spaced relation to said shell, said supporting means being disposed in said annular space and comprising: at one station a plurality of elongated, flexible strut members each disposed tangentially relative said basket, each strut member being connected to said shell at one end thereof and pivotally connected to said basket at the other end thereof, and a plurality of elongated, flexible braces at said one station converging toward a common point on said axis at an acute angle to said axis, said braces each being pivotally connected at one end to said basket adjacent the 6 respective other ends of said strut membeTs and being References Cited in the file of this patent connected at the other end to said shell; the cross-sec- UNITED STATES PATENTS tional extent of each of said braces and said strut members being substantially the same in directions which are trans- 2,268,464 Selppel 1941 verse to its longitudinal extent and at right angles to each 5 2,509,503 Huyton May 391 1950 when 2,722,801 Lombard Nov. s, 1955 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Noo 3,007,308 November 7, 1961 Thomas J. Rahaim et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 56, after "an" insert acute Signed and sealed this 10th day of April 1962.

(SEAL) Attest:

ERNEST W; SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents 

